When adding a new service such as Voice over IP (VoIP) in an Internet Protocol (IP) network, it is important to previously perform confirmation of communication and of a quality between multiple sites, or a high-load test for estimation of the number of connections enabling telephone calls and to verify a quality of the network, e.g., specification of a location of failure in the network or check on the number of connections causing degradation of a quality.
To realize such a quality test between multiple sites by using a small number of test tools (measuring instruments), a method of transmitting a test packet from a test packet transmitting apparatus provided outside a target section by using a multicast address to measure a communication quality in the target section is utilized. According to a Protocol Independent Multicast-Sparse Mode (PIM-SM), a multicast protocol, a repeating installation (router) set at a Rendezvous Point (RP) can execute multicast distribution.
In light of this function, the repeating installation is set as the RP for a test packet at a starting end of the target section where a communication quality is measured. The test packet transmitted from the test packet transmitting apparatus provided outside the target section is relayed by the repeating installation at the starting point of the target section and is received by a test packet receiving apparatus at an end point of the target section. As a result, a communication quality in the target section can be measured even if the test packet transmitting apparatus is not provided in a subnet at the starting point of the target section.
However, in the conventional technology, when the test packet transmitted from the test packet transmitting apparatus provided outside the target section is not received by the test packet receiving apparatus, it is difficult to distinguish a situation where the unreceived test packet is lost before reaching the target section from the test packet transmitting apparatus from a situation where the unreceived test packet is lost in the target section after reaching the target section.
Therefore, when the communication quality of the target section is calculated based on the number of the test packets transmitted by the test packet transmitting apparatus and the number of the test packets received by the test packet receiving apparatus, losses of test packets that occur between the test packet transmitting apparatus and the target section are included in a communication quality calculation result. Therefore, there is a problem that the communication quality of the target section cannot be accurately measured.